Dear :

I was surprised to receive your collection letter of [date] in which you reminded me that I hadn't made my payment for invoice #.

On [date], I instructed my bank, , to credit your account in [bank] with $. My bank statement of [date] shows that $ has been debited to my account, from which I can assume that the same amount of money has been credited to your account. Possibly your bank has not advised you promptly. I suggest that you check with them immediately and let me know the result of your inquiry.

Hope to hear from you soon.

Sincerely yours,

[name]

[title]